Neuronal feedback within the network regulating GnRH secretion

• Autorzy: Kallo I.
• Języki publikacji: EN

Abstrakty

EN

Besides forming the final output pathway regulating the reproductive functions of the anterior pituitary gland, GnRH neurons provide neuronal input to sites within the hypothalamus. The aim of these studies was to reveal, whether GnRH neurons interact with neuronal systems that mediate estrogenic, circadian, metabolic, lactational and/or stress-related signals to GnRH neurons. The neuronal circuitry regulating GnRH secretion was investigated by confocal and electron microscopic immunohistochemistry in rodent and human brains. In addition, interaction of GnRH neurons with other neurons within the circuitry was studied by in vitro electrophysiological experiments. Based on the observation that cannabinoids suppress fertility via reducing hypothalamic GnRH output, the presence of type 1 cannabinoid receptors in the afferents of GnRH neurons and cannabinoid release from GnRH neurons were tested in GnRHGFP mice. The obtained morphological and electrophysiological evidence supports that retrograde endocannabinoid signaling reduces GABAergic afferent drive onto GnRH neurons via the activation of presynaptic CB1 receptors. In addition to local interactions, GnRH neurons send axonal projections to neurons of the preoptic area and the arcuate nucleus, which have particular significance due to their critical role played in the control of GnRH and prolactin secretion. It was tested whether GnRH-immunoreactive (IR) projections establish morphological and functional connections with kisspeptin (KP) and dopaminergic neurones at these sites. Synaptic connections were revealed between GnRH axon terminals and KP-IR and/or tyrosine hydroxylase (TH)–IR neurons; in addition, membrane effects of GnRH were demonstrated on preoptic neurons identified post hoc the recordings. The functional significance of the discovered cannabinoid signaling, and the GnRH input to KP and dopaminergic cell populations, and the translational aspects of the rodent studies will be discussed.

• Wydawca: -
• Czasopismo: Acta Neurobiologiae Experimentalis
• Rocznik: 2015
• Tom: 75
• Numer: Supl.
• Opis fizyczny: p.S25

Twórcy

autor

Kallo I.

• Laboratory of Endocrine Neurobiology, Hungarian Academy of Sciences, Budapest, Hungary